Process of dyeing.



UNITED STATES PATENT OFFICE.

FRIEDRICH JUST, OF I-IGCHST-ON-THE-MAIN, GERMANY, ASSIGNOR TO THE FARBIVERKE, VORMALS MEISTER, LUCIUS d: BRIINING, OF SAME PLACE.

PROCESS OF DYEING.

SPECIFICATION forming part of Letters Patent No. 647,268, dated April 10, 1900.

Application filed July 19, 1899. Serial No. 724,336- (No specimens.)

To all whom it may concern.-

Be it known that I, FRIEDRICH JUST, a citizen of the Empire of Austria-Hungary, residing at Hiichst-on-the-Main, Germany, have invented certain new and useful Improvements in the Manufacture of Colors Developed by Chromium Compounds on W001 Fiber, of which the following is a specification.

In the process for producing fast colors developed by chromium compounds on wool fiber, forming part of the German Patents Nos. 66,838 and 67,240 and the English Patent .No. 9,371, of 1898, I have made an important improvement and have thus opened a new field to colors developed by chromium compounds in fast wool-d yeing. The process which takes place in producing such colors on the fiber is such that the respective azodyestuffs are first dyed in an acid-bath on the woolfiber, then oxidized by the action of chromic acid,while being transformed sim ultaneously into the chromium-oxid lakes of the oxidation products are thus formed. \Vith the present mode of working (also described in the above-cited patents) the transformation into the oxidation products, as well as the formation of their chromium-oxid lakes, is by no means complete. A part of the dyestuif, though small, is fixed on the fiber in an unchanged condition, as shown, when the fiber is milled and washed by bleeding on white material. I have made the surprising obser vation, which could not have been foreseen, that a simultaneous addition of reducing agents-such as lacticacid, lactates, tartaric acid, citric acid and its salts, bisulfite, &c.-- to the chromium fluid avoids this drawback.

If woolen yarns, for instance, be dyed with four per cent. of chrome brown, (R0), fifteen per cent. of Glaubers salt, and three per cent. of sulfuric acid in the usual manner and boiled for one hour, then on adding five per cent. of potassium bichromate, two per cent. of sulfuric acid, and three'per cent. of lactic acid and boiling for another hour a deep brown is obtained exceedingly fast to milling and not liable to bleed. If, however, there is no addition of lactic acid, a brown is obtained which bleeds on the white when the fiber is strongly milled with soap and still more so when milled with soda. It is consequently useless for dyeing loose Wool, slubbing, or yarns which, besides white or light colors, are employed for milled goods.

An efiect similar to that obtained with lactic acid is obtained with tartar, oxalic acid, tartaric acid, citric acid, bisulfite, &c.,which, like lactic acid, reduce chromic acid.

In obtaining colors developed by chromium compounds fast to milling it is also of importauce that the dye-bath at the time of the oxidizing action of the chromate should give a decidedly-acid reaction. A simultaneous addition of mineral acids with the chromate libcrating the chromic acid is therefore indispensable.

It is preferable in some cases, as stated in the second claim of the German Patent No. 66,838, to prepare the bath at the beginning, together with the dyestufi, acid, Glaubers salt, and chromate. In this case the abovementioned reducing agents, together with an excess of lactic acid, are only added after the formation of the lake on the fiber is fairly completed by boiling for about one hour.

The action of the reducing agents upon the fastness of the colors to milling is a remarkable one and may be observed with all colors developed by chromium.

The process may be illustrated by the following examples:

Example I-Darlc brownfast to milling on fifiy kilos loose wo0l.The bath is prepared with about one hundred and fifty liters of water, 7.5 kilos of Glaubers salt, 1.5 kilos of sulfuric acid, and two kilos of chrome brown, (13.0.) The wool is introduced at 40 centi: grade, brought to boil within half an hour, and boiled for one hour. Then the bath is somewhat cooled. The solution of 2.5 kilos of potassium bichromate, one kilo of sulfuric acid, and 1.25 of lactic acid is added, and the brown is developed by boiling for about one hour.

Example IIBlaclc uponfifty kilos of cheviot yarn.The bath is prepared with about two hundred of liters of water, ten kilos of Glaubers salt, two kilos of sulfuric acid, and two thousand seven hundred and fifty kilos of chromotrope S. The yarn is introduced at 40 centigrade, brought to boil in about one hour, and after boiling one hour 1.25 kilos of tartar and 1.5 kilos ofsulfuric acid are added and multancously to the action of a reducing the Whole is further boiled for about half an agent, substantially as set forth.

hour. In testimony that I claim the foregoing as Having now described my invention, What my invention I have signed my name in pres- 5 I claim is once of two subscribing Witnesses.

The process herein described of producing g on W001 fiber colors developed by chromium FRIEDRICH JUST compounds, which consists in dyeing the fiber \Vitnesses: with an azo-dyestuff, oxidizing the same with CARL J UST,

IO chromic acid, and subjecting the dyestuff si- FRANK TEDLATI). 

